Several hundred thousand patients undergo disc operations each year. Approximately five percent of these patients will suffer recurrent disc herniation, which results from a void or defect which remains in the outer layer (annulus fibrosis) of the disc after surgery involving partial discectomy.
In the disc of a healthy patient, the nucleus pulposus is entirely surrounded by the annulus fibrosis. In the case of the herniated disc, a portion of the nucleus pulposus has ruptured through a defect in the annulus fibrosis, often resulting in a pinched nerve. This results in pain and further complications, in many cases.
One accepted treatment involves a partial discectomy. Following such a procedure, a void remains adjacent a hole or defect in the annulus fibrosis following removal of the disc material. This hole may act as a pathway for additional material to protrude into the nerve, resulting in the recurrence of the herniation.
I have devised various solutions to this condition. Reference is made to my U.S. Pat. No. 6,245,107, the entire content of which is incorporated herein by reference, the subject matter of which resides in methods and apparatus for treating disc herniation, and recurrent disc herniation, in particular.
To correct defects of this type, a conformable device is provided which assumes a first shape associated with insertion and a second shape or expanded shape to occlude the defect. The device may take different forms according to the invention, including solidifying gels or other liquids or semi-liquids, patches sized to cover the defect, or plugs adapted to fill the defect.
The device is preferably collapsible into some form for the purposes of insertion, thereby minimizing the size of the requisite incision while avoiding delicate surrounding nerves. Such a configuration also permits the use of instrumentation to install the device, including, for example, a hollow tube and a push rod to expel the device or liquefied material out of the sheath for use in occluding the disc defect.
A device according to the invention may further include one or more anchors to assist in permanently affixing the device with respect to the defect. For example, in the embodiment of a mesh screen, the anchors may assume the form of peripheral hooks configured to engage with the vertebra on either side of the disc. The teachings further contemplates a distracting tool used to force the anchors into the vertebra. Such a tool would preferably feature a distal head portion conformal to the expanded shape of the device, enabling the surgeon to exert force on the overall structure, thereby setting the anchors.